Reviewing Safety Data Sheets: 5 Questions You MUST Ask Before Approving Chemical Products for Use On-Site

Did you know studies have shown a high percentage of Safety Data Sheets contain factual inaccuracies, misclassified hazards and missing hazardous ingredients (1,2)? 

Or that inaccurate or misleading flashpoints can trigger fires and explosions and have resulted in at least one workplace fatality in Alberta (4)? 

Unfortunately, it is not uncommon for some other suppliers to provide SDSs that are incorrect and are sometimes intentionally misleading. That’s why we developed this guide to help Health and Safety Professionals, Managers, Procurement Managers, Buyers and others involved in approving hazardous materials and chemical products for use on-site. 

When you’re done reading, you’ll have the tools you need to read and understand your Safety Data Sheets effectively and identify SDSs that may not be providing you with the full picture—potentially putting your workers at risk.  

Armed with this knowledge, you’ll be better prepared to assess the real hazards to ensure your workers are properly protected. 

5 Questions You MUST Ask Before Approving Chemical Products for Use On-SIte

To evaluate the accuracy of your supplier’s SDS and protect your workers, you must ask the following questions: 

  • Are you going to dilute this product? 
  • Have you considered how the product will be handled in your own operation? 
  • Is information on the SDS withheld for Confidential, Proprietary or Trade Secret claims? And are those claims registered with Health Canada and valid? 
  • Does the product have a flashpoint? If so, does it identify the method of testing? 
  • Have you reviewed the pH of the product? 

In the following sections, we’ll dive into detail on why each question is important. We’ll go over the information you should look for to get the full picture to help you assess the real hazards or question your supplier before approving a hazardous product for use. 

Are You Going to Dilute this Product?

If so, consider the potential reduction in hazard from handling the diluted product compared to the concentrate. When evaluating any SDS, it is important to remember that the SDS represents the product as supplied in concentrated form. For products that are to be diluted before use, the hazards of the diluted product are often significantly reduced and should be considered during evaluation. 

Have You Considered How the Product Will be Handled in Your Own Operation?

Will your employees be handling the product in a well-ventilated area, or will they be wearing special equipment? Are there any additional administrative or engineering controls that may be in place to reduce the hazards or requirements for PPE? 

Is Information on the SDS Withheld for Confidential, Proprietary or Trade Secret Claims?

In Canada, a Hazardous Materials Information Review Act (HMIRA) claim number is required for all confidential, proprietary and trade secret claims. Only registered claims are acceptable as Health Canada reviews the product formulation and SDS to ensure the supplier is providing accurate information to protect your workers while still protecting their confidential business information. 

Suppliers typically make these claims in sections 1 or 3 of the SDS and may seek to avoid disclosure of components, CAS numbers and concentrations. In doing so, they must still disclose all proprietary ingredients of the product but may use generic chemical names that do not reveal the full chemical identity. 

These claims must be filed through Health Canada and receive an HMIRA Claim Number to be valid. If no registration number is listed, the supplier may not be providing you with all the information needed to protect your workers and may be withholding hazard information that could impact your assessment and use within your operation. These unmitigated hazards could result in property damage, personal injury or worse (2). 

You can confirm with Health Canada if your supplier has an active claim for exemption. Active confidential business information exemptions for workplace hazardous products can be found on (3). 


1. Supplier makes proprietary claim without supporting Health Canada HMIRA registration. The supplier may be withholding key safety information. This should be a red flag that other pertinent safety information may be missing, potentially putting your workers at risk. 

X Invalid proprietary claims

2. Supplier claims Health Canada HMIRA registration but fails to supply required hazardous ingredients listing. The supplier may be withholding key safety information. This claim would not meet the criteria of Health Canada. Even if the HMIRA Number is valid this should be a red flag that other pertinent safety information may be missing potentially putting your workers at risk.

X No hazardous ingredient information

3. Supplier claims Health Canada HMIRA registration and complies with legislation.

HMIRA registration and proper hazardous ingredients listing

Does the Product Have a Flashpoint? If so, Does it Identify the Method of Testing?

For WHMIS and TDG classification, flashpoints should be determined using a closed cup method. This would be identified as closed cup, Cleveland closed cup (CCC) or Tag closed cup (TCC). 

If no method is listed, or an open cup method is used the information on the SDS may be inaccurate. It is acceptable for a supplier to list both open and closed cup flashpoints, but the closed cup flashpoint must be used for classification and should be the number used when comparing products. Inaccurate flashpoints can trigger fires and explosions and have resulted in at least one workplace fatality in Alberta (4). 

Have You Reviewed the pH of the Product?

This can be found under section 9 (physical properties). Products with a pH >11.5 or <2.0 should be identified as corrosive by both WHMIS and TDG. 

Some suppliers mis-classify corrosive products as irritants and classify the product as less hazardous than it really is. 

You may encounter SDSs that list pH for both the concentrate and the diluted product, it is acceptable to list both, however classification for water based products must be derived from the concentrate. 

Your Partner in Environment, Health, and Safety

At Guardian Chemicals, we care about your health and safety. All our solutions are designed with you, the user in mind. This means our products are easier to use, safer, and more environmentally responsible than the alternatives. 

We will not compromise when it comes to the Environment or your Health and Safety.  We strive to provide you with the most accurate and reliable product information to help you make informed decisions about the products you choose and how to use them safely. 

If you have questions regarding Safety Data Sheets or our products, call us at (780) 998-3771 or toll free at 1 (800) 661-6544. 

And, if you can’t get the help you need from your current supplier, contact us to learn how we can help you Create a Better Future. A future where your chemical supplier is a partner who helps you understand the risks so you can safely handle the chemicals for your application. 

1. Nicol, A. M., Hurrell, A. C., Wahyuni, D., McDowall, W., & Chu, W. (2008, November). Accuracy, comprehensibility, and use of material safety data sheets: A review. American Journal of Industrial Medicine 51, 861-876.

2. Welsh, M. S., Lamesse, M., & Karpinski, E. (2000). The verification of hazardous ingredients disclosures in selected material safety data sheets. Applied Occupational and Environmental Hygiene, 15(5), 409–420.

3. List of claims and exemptions under the Hazardous Materials Information Review Act, accessed 16 August 2023


4. Radnoff, D. (2013). Accuracy of reported flash point Values on Material Safety Data Sheets and the Impact on Product Classification. Journal of Occupational and Environmental Hygiene, 10(10), 540–546.

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